Rotary joint

ABSTRACT

This transmission joint comprises a first and a second rotary member, a boot ( 7 ) connected by a front end region to the first rotary member and by a rear end region ( 33 ) to the second rotary member ( 6 ), and means for axially retaining the rear end region of the boot with respect to the second rotary member which comprise a retaining enlargement ( 20 ) and a groove ( 38 ) for housing the retaining enlargement, the rear end region ( 33 ) of the boot and the second rotary member having matching transverse outlines of which the directrix curves exhibit points of inflection. The enlargement is situated on the periphery of the second rotary member and spaced axially from the front end ( 22 ) of the second rotary member, and the groove ( 38 ) is formed on the periphery of the boot.

BACKGROUND OF THE INVENTION

The present invention relates to a transmission joint of the typecomprising a first and a second rotary member, a boot connected by afront end region to the first rotary member and by a rear end region tothe second rotary member, and means for axially retaining the rear endregion of the boot with respect to the second rotary member whichcomprise a retaining enlargement and a groove for housing the retainingenlargement, the rear end region of the boot and the second rotarymember having matching transverse outlines of which the directrix curvesexhibit points of inflection.

The invention applies in particular to tripot constant-velocitytransmission joints.

Such joints allow a rotary movement to be transmitted between a firstshaft bearing a male element or tripod and a female element or bellhousing which rotates as one with, for example, the output side gear ofa differential.

The tripod has three arms each bearing a rolling assembly. Each rollingassembly is intended to roll on a pair of tracks formed in the bellhousing. The tripod and the bell housing have ternary symmetry.

The rear end region of the boot is slipped over a front end region ofthe bell housing.

The bell housing is produced in particular by forging and, in crosssection, has, in alternation, convex parts and concave or flat parts.The terms “convex” and “concave” are to be understood as meaning withrespect to the outside of the bell housing. The convex parts are fartherfrom the longitudinal axis of the bell housing than the concave or flatparts.

The groove that houses the retaining enlargement is therefore made ineach of the convex parts from the radially outer surface of the bellhousing. The retaining groove therefore extends discontinuously aroundthe periphery of the bell housing.

The enlargement extends peripherally in a corresponding way on theradially inner surface of the boot.

A clamping member clamps the rear end region of the boot onto the frontend region of the bell housing, holding the retaining enlargement insidethe housing groove.

The housing groove is generally formed in the bell housing by turning.Because of the discontinuous nature of the groove, such a machiningoperation poses numerous problems including relatively high wear of thecutting tool used, and the difficulty of producing a groove whosevarious portions are concentric.

Furthermore, the number of portions of the housing groove and theirangular extent depends on the number of convex parts of the bell housingand on their angular extent.

Thus, the total angular extent of the retaining housing groove may berelatively small and the axial retention of the rear end of the bootwith respect to the bell housing may therefore not be satisfactory.

SUMMARY OF THE INVENTION

The object of the invention is to solve these problems by providing atransmission joint of the aforementioned type that makes it possible tolimit the difficulties of machining the bell housing and to increase theangular extent of the groove that houses the retaining enlargement for agiven transverse profile of bell housing.

To this end, the subject of the invention is a transmission joint of theaforementioned type, characterized in that the enlargement is situatedon the periphery of the second rotary member and spaced axially from thefront end of the second rotary member and in that the groove is formedon the periphery of the boot.

According to particular embodiments, the transmission joint may includeone or more of the following features, taken in isolation or in anytechnically feasible combination:

the retaining enlargement and the groove that houses the retainingenlargement have roughly matching longitudinal profiles,

the retaining enlargement extends discontinuously around the peripheryof the second rotary member,

the retaining enlargement comprises several portions spaced roughlyregularly about the periphery of the second rotary member,

the groove that houses the retaining enlargement extends around theperiphery of the boot in a similar way to the retaining enlargementaround the periphery of the second rotary member,

the boot comprises sealing means located axially on the same side withrespect to at least part of the groove that houses the retainingenlargement,

the sealing means are located axially on the same side with respect tothe entirety of the groove that houses the retaining enlargement,

the sealing means are located axially to the rear of said part of or theentirety of the groove that houses the retaining enlargement,

the sealing means are located radially on the same side of the boot asthe housing groove,

it comprises a member for clamping the rear end of the boot onto thesecond rotary member,

the clamping member is located axially, with respect to at least part ofthe groove that houses the retaining enlargement, on the same side asthe boot sealing means,

the retaining enlargement is situated on a radially outer surface of thesecond rotary member and in that the housing groove is formed on aradially inner surface of the boot,

the retaining enlargement is formed on the second rotary member byupsetting the material of the second rotary member.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from reading thedescription which will follow, given merely by way of example and madewith reference to the appended drawings in which:

FIG. 1 is a longitudinal diagrammatic view in partial section of atransmission joint according to the invention,

FIG. 2 is a front view illustrating the transverse profile of the bellhousing of the joint of FIG. 1,

FIGS. 3 to 5 are enlarged diagrammatic part views in section on III—III,IV—IV and V—V, respectively, of FIG. 2,

FIG. 6 is a view similar to FIG. 2 illustrating another embodiment ofthe transmission joint of FIG. 1, and

FIGS. 7 and 8 are enlarged partial diagrammatic views in sectionrespectively on VII—VII and VIII—VIII of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a tripot constant-velocity joint 1.

This joint 1, with ternary symmetry about an axis X—X in its alignedposition depicted in FIG. 1, essentially comprises:

a male element or tripod 3 comprising three arms 4 distributed angularly120° apart and each bearing a rolling assembly 5,

a female element or bell housing 6, and

an elastic boot 7.

The tripod 3 is borne by a rotary shaft 8.

The bell housing 6 comprises a body 10 extended to the rear (to theright in FIG. 1) by a shank 11 intended to be connected, by splines 12,for example, to the shaft of an output side gear of a differential, notdepicted.

The body 10 comprises a bottom end 13 which bears the shank 11 and whichis extended forward by a sidewall 14.

As can be seen in FIG. 2, the wall 14 has a cylindrical transverseoutline with respect to the longitudinal axis X—X of the bell housing 6,whose directrix curve exhibits points of inflection. Thus, the wall 14has six convex parts 16, three concave parts 17 and three flat parts 18.

The terms “convex” and “concave” are to be understood as meaning withrespect to the outside of the bell housing 6.

The exterior transverse outline of the convex parts 16 over most of theaxial length of the wall 14 is depicted in dotted line in FIG. 2.

The convex parts 16 are distributed at regular angles about thelongitudinal axis X—X. These convex parts 16 are joined togetheralternately by the convex parts 17 and flat parts 18.

Each convex part 16 is farther from the longitudinal axis X—X of thebell housing 6 than the concave parts 17 and flat parts 18.

The convex parts 16 connected by one and the same flat part 18internally delimit a pair of tracks 19 on which a rolling assembly 5 isintended to run.

A discontinuous peripheral enlargement 20 of axis X—X projects from theradially outer surface 21 of the sidewall 14 of the bell housing 6. Theenlargement 20 is spaced axially a short distance away from the frontedge face or end 22 of the bell housing 6.

The enlargement 20 has a portion 23 at each convex part 16.

The enlargement 20 is interrupted at each concave part 17 or flat part18 of the sidewall 14 of the bell housing 6 as can be seen in FIGS. 2, 4and 5. The top 24 of this enlargement 20 belongs to a cylinder ofcircular cross section and axis X—X.

As illustrated by FIG. 3, the front flank 25 of each portion 23 of theenlargement 20 is orthogonal to the axis X—X and the rear flank 26 ofeach portion 23 of the enlargement 20 is inclined with respect to theradial direction, outward and toward the front of the bell housing 6.

Each front flank 25 of a portion 23 has a greater radial extent than therear flank 26 of the same portion 23. Each front flank 25 is connectedto the front edge face 22 of the bell housing 6 by, in succession, aregion 27 of the surface 21, with generatrices parallel to the axis X—X,and a chamfered region 28 which is inclined with respect to the axis X—Xforward and toward the inside of the bell housing 6.

The six chamfered regions 28 located forward of the portions 23 of theenlargement 20 are distributed at regular angles about the axis X—X.

The bell housing 6 has been produced by forging, and then the chamferedregions 28 have been machined by turning and the portions 23 of theenlargement 20 formed by upsetting material toward the rear of the bellhousing 6. The regions 27 of the radially outer surface 21 have beenformed during this upsetting. The front edge face 22 can remain, that isto say undergo no subsequent machining operation.

As can be seen in FIG. 1, a front end region 30 of the boot 7 is fixedto the first shaft 8, some distance from the tripod 3, by a clampingcollar 31.

In a rear end region 33, the boot 7 has an internal cross section of ashape which in general matches that of the radially outer surface 21 ofthe sidewall 14 of the bell 6.

The rear end region 33 of the boot 7 is slipped over a front end region34 of the bell housing 6 which comprises the retaining enlargement 20.

As can be seen in FIGS. 3 to 5, the rear end region 33 of the boot 7comprises, in succession, from the rear edge face or end 35 of the boot7, two peripheral and continuous sealing lips 37 which extend radiallyinward around the entire periphery of the boot 7, and a peripheralgroove 38 for housing the enlargement 20 of the bell housing 6.

The groove 38 extends peripherally around the boot 7 In a similar way tothe enlargement 20 around the periphery of the bell housing 6. Thus, thegroove 38 has several portions 39 regularly angularly spaced apart.

The longitudinal profile of the radially inner surface of the boot 7near the groove 38 is, except as far as the sealing lips 37 areconcerned, a match for that of the radially outer surface 21 of the bellhousing 6 near the enlargement 20.

Thus, the groove 38 has a bottom 42, a front flank 43 and a rear flank44 which are of shapes which match those of the top 24, the front flank25 and the rear flank 26 of the enlargement 20, respectively, and whichare pressed against these.

Furthermore, a region 46 of the radially inner surface of the boot 7 ispressed against the region 27 of the radially outer surface 21 of thesidewall 14 of the bell housing 6.

The radially outer surface of the rear end region 33 of the boot 7exhibits approximate symmetry of revolution about the axis X—X and,axially to the rear of the bottom 42 of the groove 38, has a groove 49for housing a clamping collar 50. This clamping collar 50 extendsaxially over the sealing lips 37. The clamping collar 50 is housed witha small amount of axial clearance in the groove 49.

The seal between the rear end region 33 of the boot 7 and the front endregion 34 of the bell housing 6 is provided satisfactorily by the lips37 which are compressed around the entire periphery of the radiallyouter surface 21 of the bell housing 6 by the clamping collar 50.

Furthermore, the rear end region 33 of the boot 7 is retained axially inboth axial directions with respect to the bell housing 6 by theenlargement 20 and the retaining groove 38.

It will be noted that the axial extent of the clamping collar, althoughlimited, provides satisfactory retention of the boot 7 with respect tothe bell housing 6 by virtue of the enlargement 20 and of the groove 38.

What is more, the machining to be performed on the bell housing 6 toallow this axial retention of the boot 7 with respect to the bellhousing 6 is relatively simple to perform and the tools used are damagedrelatively little.

It is interesting to note that the chamfered regions 28 from which theenlargement 20 is formed by upsetting the material of the bell housing 6are surfaces which are usually machined on the bell housings 6 of tripotjoints 1 to center the bell housing 6 during finishing by rolling thesplines 12 of the shank 11 of this bell housing 6.

In the embodiment of FIGS. 1 to 5, the enlargement 20 has as manyportions 23 as the sidewall 14 of the bell housing 6 has convex parts16. The total angular extent of the enlargement 20 therefore correspondsto the total angular extent of these convex parts 16. However, as willnow be described with reference to FIGS. 6 to 8, it is possible toproduce a retaining enlargement 20 whose total angular extent is greaterthan the total angular extent of the parts 16 of the sidewall 14farthest from the longitudinal axis X—X of the bell housing 6.

FIG. 6 illustrates a bell housing 6 which differs mainly from that ofFIGS. 1 to 5 in that the enlargement 20 that retains the boot 7comprises nine portions 23. Each concave part 17 of the sidewall 14 hasa portion 23 of the enlargement 20, and each flat part 18 has twoportions 23 of the enlargement 20. The portions 23 of the enlargement 20of each flat part 18 are identical and angularly spaced apart. The outertransverse outline of the concave parts 17 and flat parts 18 over mostof the axial length of the wall 14 is depicted partially in dotted linein FIG. 6.

As illustrated in FIG. 7, each front flank 25 of the enlargement 20 isconnected to the front edge face 22 of the bell housing 6 by a region 27of the radially outer surface 21 of the bell housing 6. Each region 27has generatrices parallel to the longitudinal axis X—X of the bellhousing 6.

Furthermore, the boot 7 internally has an axial shoulder 60 whichextends peripherally inside the boot 7 a short axial distance away fromthe front edge face 22 of the bell housing 6.

The embodiment in FIGS. 6 to 8 makes it possible to have a retainingenlargement 20 whose total angular extent is markedly greater than thatof the convex parts 16 of the sidewall 14 of the bell housing 6. Inaddition, the portions 23 of the enlargement 20 are more closelyangularly spaced than in the transmission joint of FIGS. 1 to 5.

The axial retention of the boot 7 with respect to the bell housing 6 isthus satisfactory and the risk of the boot 7 gaping when thetransmission joint is in operation are limited.

It is to be noted that the axial shoulder 60 of the boot 7 may also playa part in axially retaining the boot 7 with respect to the bell housing6 when the rear end region 33 of the boot 7 tends to move backward withrespect to the bell housing 6. To play a part in such retention, theshoulder 60 comes into abutment against the edge face 22 of the bellhousing 6.

In an alternative form which is not depicted, it is possible to machinethe front edge face 22 of the bell housing 6 so that it comes intocontact with the shoulder 60 of the boot 7 around practically its entireperiphery when the boot 7 is stressed axially.

I claim:
 1. A transmission joint (1) comprising: a first rotary member (8); a second (6) rotary member; a boot connected by a front end region (30) to the first rotary member and by a rear end region (33) to the second rotary member; and means for axially retaining the rear end region of the boot with respect to the second rotary member comprising a retaining enlargement (20) and a groove (38) for housing the retaining enlargement, the rear end region (33) of the boot and the second rotary member having matching transverse outlines of which the directrix curves exhibit points of inflection, wherein the enlargement (20) is situated on the periphery of the second rotary member (6) and spaced axially from the front end (22) of the second rotary member and wherein the groove (38) is formed on the periphery of the boot (7).
 2. The joint as claimed in claim 1, wherein the retaining enlargement (20) and the groove (38) that houses the retaining enlargement have roughly matching longitudinal profiles.
 3. The joint as claimed in claim 1, wherein the retaining enlargement (20) extends discontinuously around the periphery of the second rotary member (6).
 4. The joint as claimed in claim 3, wherein the retaining enlargement (20) comprises several portions (23) spaced substantially regularly about the periphery of the second rotary member (6).
 5. The joint as claimed in claim 1, wherein the groove (38) that houses the retaining enlargement (20) extends around the periphery of the boot (7) in a similar way to the retaining enlargement (20) around the periphery of the second rotary member (6).
 6. The joint as claimed in claim 1, wherein the boot (7) comprises sealing members (37) located axially on the same side with respect to at least a part of the groove that houses the retaining enlargement.
 7. The joint as claimed in claim 6, wherein the sealing members (37) are located axially on the same side with respect to the entirety of the groove (38) that houses the retaining enlargement (20).
 8. The joint as claimed in claim 6, wherein the sealing members (37) are located axially to the rear of at least a part of the groove (38) that houses the retaining enlargement (20).
 9. The joint as claimed in claim 6, wherein the sealing members (37) are located radially on the same side of the boot as the housing groove (38).
 10. The joint as claimed in claim 6, comprising a member (50) for clamping the rear end of the boot onto the second rotary member, wherein the clamping member (50) is located axially, with respect to at least a part of the groove (38) that houses the retaining enlargement (20), on the same side as the boot sealing members (37).
 11. The joint as claimed in claim 1, comprising a member (50) for clamping the rear end of the boot onto the second rotary member.
 12. The joint as claimed in claim 1, wherein the retaining enlargement (20) is situated on a radially outer surface (21) of the second rotary member (6) and wherein the housing groove is formed on a radially inner surface of the boot (7).
 13. The joint as claimed in claim 1, wherein the retaining enlargement (20) is formed on the second rotary member by upsetting the material of the 